evolution. what is evolution? evolution, or change over time, is the process by which modern...

EvolutionEvolution

What is Evolution?What is Evolution?

EvolutionEvolution, or , or change over timechange over time, is the , is the process by which modern populations process by which modern populations have descended from preceding have descended from preceding populations of organisms.populations of organisms.

Who is Charles Darwin?Who is Charles Darwin?

Charles Darwin – born in EnglandCharles Darwin – born in EnglandJoined the crew of the Joined the crew of the

H.M.S. BeagleH.M.S. Beagle Sailed Sailed around the worldaround the worldMade numerous observationsMade numerous observations and collected evidence that and collected evidence that led him to propose his led him to propose his hypothesis.hypothesis.

Darwin

Malthus:

Hutton & Lyell: Lamarck:

Early scientists:

past vs. present

organisms

ancient earth

acquired traits

population growth

Natural Selection

What did Darwin observe during his voyage?What did Darwin observe during his voyage?

Patterns of Diversity:Patterns of Diversity:

• Puzzled by distribution of different species (where they Puzzled by distribution of different species (where they lived and did not live)lived and did not live)

• He AskedHe Asked (for example) (for example): : * Why were there no rabbits in Australia, despite the * Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them?presence of habitats that seemed perfect for them? * Why were there no kangaroos in England?* Why were there no kangaroos in England? * Why do they look so similar?* Why do they look so similar?

What did Darwin observe during his voyage?What did Darwin observe during his voyage?

Living Organisms & FossilsLiving Organisms & Fossils

• Darwin collected and preserved fossilsDarwin collected and preserved fossils

• FossilsFossils: some: some resembled organisms that were still resembled organisms that were still alive – others looked completely unlike any creature alive – others looked completely unlike any creature he had ever seen.he had ever seen.

He AskedHe Asked: Why had so many of these species : Why had so many of these species

disappeared?disappeared?

Looks LIKE a Kangaroo

Looks nothing like any living species

What did Darwin Observe?What did Darwin Observe?

The Galapagos IslandsThe Galapagos Islands

• Most influential place Darwin visitedMost influential place Darwin visited

• Although islands were so close together, the islands had very Although islands were so close together, the islands had very different climates.different climates.

• Fascinated by the land tortoises, marine iguanas, & finches.Fascinated by the land tortoises, marine iguanas, & finches.

Where are the Galapagos Islands?Where are the Galapagos Islands?

A

BC

D

CatchIT Question:

What did Darwin observe on the What did Darwin observe on the Galapagos Islands?Galapagos Islands?

Click to zoom into Galapagos Islands

What did Darwin observe on the Galapagos Islands?What did Darwin observe on the Galapagos Islands?

* Domed shell w/ short neck

* Live on wetter islands

* Have short necks that can reach grasses and vegetation on the ground

Galapagos Tortoises


* Flatter shell compared to domed

* Live on slightly drier islands

* Have longer necks than domed to reach short bushes and trees


* “Saddle” w/ VERY long necks

* Live on dry islands

* Dry climates have less vegetation on the ground

* Long neck used to reach vegetation up in bushes & trees growing off the ground

Galapagos Tortoises Galapagos Tortoises

Click here for video


• All tortoises resemble a species living in South AmericaAll tortoises resemble a species living in South America

• Saw that giant tortoises varied in predictable ways from Saw that giant tortoises varied in predictable ways from one island to another.one island to another.

• The shape of a tortoise’s shell could be used to identify The shape of a tortoise’s shell could be used to identify which island a particular tortoise lived.which island a particular tortoise lived.

Natural Selection QuestionsNatural Selection Questions(Bill Nye)(Bill Nye)

1.1. A young man that walked out was __ ___.A young man that walked out was __ ___.2.2. He quit medical school to become a ___.He quit medical school to become a ___.3.3. How long did the Beagle stay in the Galapagos How long did the Beagle stay in the Galapagos

Islands? __ daysIslands? __ days4.4. Finches had different shaped ___: varied by Finches had different shaped ___: varied by

the environment they inhabited.the environment they inhabited.5.5. What was the mechanism that made evolution What was the mechanism that made evolution

occur? ___ ____occur? ___ ____6.6. When did he publish his book?When did he publish his book?7.7. Now, every where we look at today, we see Now, every where we look at today, we see

something that came from ___.something that came from ___.

Natural Selection Clip Natural Selection Clip (Bill Nye)(Bill Nye)

Click here for video

Who influenced Darwin’s ideas?Who influenced Darwin’s ideas?

Recognized that Earth is Recognized that Earth is many millionsmany millions of of years old.years old.

And the processes that changed Earth in And the processes that changed Earth in the past are the same processes that the past are the same processes that operate in the present.operate in the present.

James Hutton and Charles Lyell James Hutton and Charles Lyell

(geologists)

Hutton and Lyell Hutton and Lyell said…said…

Volcanoes release hot lava and gases now, just Volcanoes release hot lava and gases now, just as they did on an ancient Earth.as they did on an ancient Earth.

Erosion continues to carve out canyons, just as Erosion continues to carve out canyons, just as it did in the past.it did in the past.

Also said that awesome geological features Also said that awesome geological features could be built up or torn down over long periods could be built up or torn down over long periods of time.of time. (examples: earthquakes and volcanoes) (examples: earthquakes and volcanoes)

Wild/Crazy Idea:Wild/Crazy Idea: Earth Earth changeschanges over time over time

Hutton and LyellHutton and Lyell

So……Because of Hutton & Lyell’s work…..So……Because of Hutton & Lyell’s work…..

Darwin then askedDarwin then asked: :

If the Earth could change over time, If the Earth could change over time,

might might lifelife change as well? change as well?

Who else influenced Darwin’s Ideas?Who else influenced Darwin’s Ideas?Malthus (an economist) – Studied population Malthus (an economist) – Studied population

growth - observed that babies were being born growth - observed that babies were being born faster than people were dying.faster than people were dying.

He reasoned that if the human population He reasoned that if the human population

continued to grow unchecked, sooner or continued to grow unchecked, sooner or later there would be insufficient living space later there would be insufficient living space and food for everyone.and food for everyone.

Lamarck’s Theory of EvolutionLamarck’s Theory of Evolution

Proposed that by selective Proposed that by selective useuse or or disusedisuse of of organs, organisms organs, organisms acquiredacquired or lost certain traits or lost certain traits during their lifetime.during their lifetime.

These traits could then be passed on to their These traits could then be passed on to their offspring.offspring.

Over time, this process led to change in a speciesOver time, this process led to change in a species

Who else was thinking about evolution?

Was he “right”?

Lets break it down….

How did Lamarck think organisms changed?How did Lamarck think organisms changed?

Fiddler Crabs: An ExampleFiddler Crabs: An Example

1. The male crab uses its small front 1. The male crab uses its small front claw to attract mates and ward off claw to attract mates and ward off predatorspredators

2. Because the front claw has been 2. Because the front claw has been used repeatedly, it becomes used repeatedly, it becomes larger (acquired).larger (acquired).

3. A larger claw, is then passed on to 3. A larger claw, is then passed on to the crab’s offspring.the crab’s offspring.

He was WRONG! He did not realize He was WRONG! He did not realize that the large claw traits were that the large claw traits were inheritedinherited

Lamarck’s Theory Lamarck’s Theory

According to Lamarck's According to Lamarck's theory, a given giraffe could, theory, a given giraffe could, over a lifetime of straining to over a lifetime of straining to reach high branches, reach high branches, develop an elongated neck, develop an elongated neck, which would then be passed which would then be passed on to the next generation. on to the next generation.

The long neck is The long neck is ACQUIREDACQUIRED

Another Example:

What were Darwin’s arguments in his book?What were Darwin’s arguments in his book?

Natural Variation and Artificial SelectionNatural Variation and Artificial Selection

• Argued that species were Argued that species were NOTNOT perfect and perfect and unchanging.unchanging.

• Natural VariationNatural Variation: There are differences: There are differences

among individuals of a species.among individuals of a species.

What is Natural Variation?What is Natural Variation?

Peppered moths come in two

versions

White Version/Morph

Black Version/Morph

If trees in an area have dark bark, the black version blends in better and is less likely to be eaten by predators.

If trees in an area have white bark, the white version blends in better and is less likely to be eaten by predators.

Take home message: The Take home message: The natural variation may give natural variation may give

certain members an certain members an advantage over others.advantage over others.

On the Origin of SpeciesOn the Origin of Species

The actual title of his book is:The actual title of his book is:

On the Origin of Species by Means of Natural SelectionOn the Origin of Species by Means of Natural Selection

• The book proposed a mechanism for The book proposed a mechanism for evolution that he called evolution that he called natural selectionnatural selection..

• He presented evidence that demonstrates He presented evidence that demonstrates the process of evolution has been taking the process of evolution has been taking place for millions of years.place for millions of years. Darwin was 50 when it was

published!

Darwin’s Book

What is Natural Variation?What is Natural Variation?Bessie Elsie

* Elsie’s natural variation is to produce more milk than Bessie

* Which cow would the farmer use to reproduce offspring? Why?

What were Darwin’s What were Darwin’s arguments in his book?arguments in his book?

Artificial SelectionArtificial Selection: Nature provided the : Nature provided the variation among different organisms, and variation among different organisms, and humanshumans selected those variations that they selected those variations that they found useful.found useful.

* Only the largest hogs, fastest horses, and the * Only the largest hogs, fastest horses, and the cows that gave the most milk were selected to cows that gave the most milk were selected to breed and produce offspring.breed and produce offspring.

Darwin’s Evolution by Natural SelectionDarwin’s Evolution by Natural Selection

The Struggle for ExistenceThe Struggle for Existence: members within : members within each species compete regularly to obtain food, each species compete regularly to obtain food, living space, and other necessities of life.living space, and other necessities of life.

A predator that is the fastest or has a A predator that is the fastest or has a specialized way of catching prey can catch specialized way of catching prey can catch more prey.more prey.

Prey that are faster, better Prey that are faster, better

camouflaged, or better protected camouflaged, or better protected

avoid being caught.avoid being caught.

Darwin’s Evolution by Natural SelectionDarwin’s Evolution by Natural Selection

Survival of the FittestSurvival of the Fittest: Process by which : Process by which individuals that are better suited to their individuals that are better suited to their environment survive and reproduce most environment survive and reproduce most successfully; also called successfully; also called Natural SelectionNatural Selection..

Darwin called the ability of an individual to Darwin called the ability of an individual to survivesurvive AND AND reproducereproduce in its specific in its specific environment environment fitnessfitness..

An An adaptationadaptation is any inherited characteristic is any inherited characteristic that increases an organism’s chance of that increases an organism’s chance of survival.survival.

Darwin’s Discoveries Video ClipDarwin’s Discoveries Video Clip

Survival of the Fittest Survival of the Fittest

The concept of The concept of fitnessfitness, Darwin argued, was , Darwin argued, was central to the process of evolution by natural central to the process of evolution by natural selection.selection.

Example: Example:

Baby birds compete for food in the nest. The Baby birds compete for food in the nest. The stronger bird may take food from the weaker stronger bird may take food from the weaker siblings. Then…how is this related to fitness? siblings. Then…how is this related to fitness?

Evolution by Natural SelectionEvolution by Natural Selection

Descent with ModificationDescent with Modification: Concept that each : Concept that each living species has descended, with changes, living species has descended, with changes, from other species over time.from other species over time.

• Implies that all living organisms are related to Implies that all living organisms are related to one another.one another.

Common DescentCommon Descent: The principle that says all : The principle that says all species – living and extinct – were derived from species – living and extinct – were derived from common ancestors.common ancestors.

Evidences of Evolution

There are 4 categories

Evidence #1:

FOSSIL RECORD

What are some evidence of Evolution?What are some evidence of Evolution?

Fossil RecordFossil Record

Fossils that had formed in Fossils that had formed in the different layers of rock the different layers of rock were evidence of gradual were evidence of gradual change over time.change over time.

One could view how a One could view how a species had changed and species had changed and produced different species produced different species over time.over time.

Evolution of Horses

- Horses do not look the same as they did many years ago

- Fossil Record shows evidence that animals have changed over time and that they share common ancestors based on similarities in their skeletons.

Evidence #2:

COMPARATIVE ANATOMY

Homologous StructuresHomologous Structures: : Structures that have Structures that have different mature forms in different organisms but different mature forms in different organisms but develop from the same type of embryonic tissues.develop from the same type of embryonic tissues.

What are some evidences of Evolution?What are some evidences of Evolution?

These structures These structures provide evidence provide evidence for common for common ancestry and ancestry and evolution.evolution.

Vestigial StructuresVestigial Structures

• Vestigial StructuresVestigial Structures are structures that are the are structures that are the reduced forms of functional structures in reduced forms of functional structures in different species.different species.

ExamplesExamples: :

1. 1. Snake PelvisSnake Pelvis: The pelvis is the attachment : The pelvis is the attachment point for legs and is therefore nonfunctional in point for legs and is therefore nonfunctional in an animal without legsan animal without legs

Vestigial StructuresVestigial Structures2. Kiwi Wing: The wings of kiwis are too small to 2. Kiwi Wing: The wings of kiwis are too small to

be of any use in flightbe of any use in flight

3. Human Appendix: Important for digestion in 3. Human Appendix: Important for digestion in many mammals, but of limited use in humans & many mammals, but of limited use in humans & some apessome apes

• Analogous structuresAnalogous structures can be superficially can be superficially similar in construction, but are NOT inherited similar in construction, but are NOT inherited from a common ancestor. from a common ancestor.

• ExampleExample: The wing of an eagle & the wing of a : The wing of an eagle & the wing of a insect have the same function (both enable the insect have the same function (both enable the organism to fly) – but are constructed in organism to fly) – but are constructed in different ways & from different materials.different ways & from different materials.


* While analogous structures do not indicate * While analogous structures do not indicate close evolutionary relationships, they do show close evolutionary relationships, they do show that functionally similar features can evolve that functionally similar features can evolve independently in similar environments.independently in similar environments.


Evidence #3:

COMPARATIVE EMBRYOLOGY

Similarities in Early DevelopmentSimilarities in Early Development

In their early stages of development, chickens, In their early stages of development, chickens, turtles, and rats look similar, providing evidence turtles, and rats look similar, providing evidence that they shared a common ancestry.that they shared a common ancestry.


Evidence #4:

COMPARATIVE BIOCHEMISTRY

What we know… All cells rely on DNA to make proteins.

Using new technologies, biologists are able to determine the amino acid sequences in proteins to determine evolutionary relationships among various species of organisms.

The more closely related two species are, the greater the similarity in amino acid sequences of their

proteins.

For example:

Evolution VideoEvolution Video

Click here for video clip: Click here for video clip:

Darwin, the Beagle, and Finches: Darwin Discovers Evidence of Natural Selection

Types of Evolution

There are 5 main types

Divergent Evolution:When two species move away from the traits that they share with a common ancestor as

they adapt to their own environments

Also called

Adaptive Radiation…

Produces

homologous structures,

And are more CLOSELY related!

Convergent Evolution:When two distinct species with differing

ancestries evolve to display similar features.

Produces

analogous structures,

And are NOT closely related!

Sugar Glider:

Flying Squirrel

Australian marsupial

A GA squirrel

**Coevolution****Coevolution**

CoevolutionCoevolutionPollenation Pollenation

Geographic Distribution of Living SpeciesGeographic Distribution of Living Species

- Species now living on different continents had each descended from different ancestors.

- Because some animals on each continent were living under similar ecological conditions, they were exposed to similar pressures of natural selection.

• They ended up evolving certain striking features in common…

but are NOT related!

• This is called Convergent Evolution

Punctuated EquilibriumEvolution that has long periods of stability or

“unchange” followed by short periods of rapid change.

Gradualism A change that is very slow over time. It’s hard to notice a difference over a short period of time…it is slow and gradual.

5. Biological ResistanceSome organisms obtain a mutation that makes them resistant to a toxin (antibiotic or pesticide).

Overuse of antibiotics & pesticides create populations of “super bugs”.

This is why you need to take your antibiotics for the entire time…

You expose the bacteria to the toxin; but if you don’t kill them all (take all

your medicine), then you “taught them” how to resist the antibiotic!

Explanation of how resistance happens:http://www.sumanasinc.com/scienceinfocus/sif_antibiotics.html

Explanation of how bacteria transmit resistance:http://survivalrivals.org/the-x-bacteria/animation

Resistance

Video about antibiotic resistance: http://www.youtube.com/watch?v=W-WumllRPLI

Remember the graph…?

Fre

qu

ency

of

Ph

eno

typ

e

Generic Bell Curve for Natural Variation Generic Bell Curve for Natural Variation in a Complex Traitin a Complex Trait

5. Other patterns of selection

Key

Per

cen

tag

e o

f P

op

ula

tio

n

Birth Weight

Selection against both extremes keep curve narrow and in same place.

a. a. StabilizingStabilizing Selection Selection

Low mortality, high fitness

High mortality, low fitness

Stabilizing Selection

What good reasons can you come up with for this trend?

Human babies that have a really low birth weight…

Human babies that have a really high birth weight…

5. Other patterns of selection

In stabilizing selection, the In stabilizing selection, the bulk bulk portion of the bell-shaped curve is portion of the bell-shaped curve is favored;favored;

The The averageaverage phenotype is favored phenotype is favored

Directional Selection

Food becomes scarce.

Key

Low mortality, high fitness


b. b. DirectionalDirectional Selection Selection

In directional selection, the In directional selection, the one one sideside of the bell-shaped curve is of the bell-shaped curve is favored;favored;

The The one extreme one extreme phenotype is phenotype is favored over the other, over the favored over the other, over the averageaverage

Disruptive Selection

Largest and smallest seeds become more common.

Nu

mb

er o

f B

ird

sin

Po

pu

lati

on

Beak Size

Population splits into two subgroups specializing in different seeds.

Beak Size

c. c. DisruptiveDisruptive Selection Selection

Nu

mb

er o

f B

ird

sin

Po

pu

lati

on

KeyLow mortality, high fitness


In disruptive selection, In disruptive selection, both end both end portionsportions of the bell-shaped curve of the bell-shaped curve are favored;are favored;

Both extreme Both extreme phenotypes are phenotypes are favored over the averagefavored over the average

Adaptation:Adaptation:body parts, body coverings, or body parts, body coverings, or

behaviors that help an organism behaviors that help an organism survive its environment or survive its environment or reproduce more effectivelyreproduce more effectively

Adaptations:Adaptations:

MimicryMimicry: Adaptation in which one species : Adaptation in which one species evolves to resemble another species for evolves to resemble another species for protection or other advantages.protection or other advantages.

Adaptations:Adaptations:

CamouflageCamouflage: Adaptation : Adaptation

that allows organisms to blend that allows organisms to blend

into their surrounds.into their surrounds.

Adaptations:Adaptations: ImprintingImprinting: a form of learning in which a very : a form of learning in which a very

young animal fixes its attention on the first young animal fixes its attention on the first object experience and then follows that object object experience and then follows that object

Plants:Plants:Tropisms (Growth Responses): Tropisms (Growth Responses):

1) Phototropism: Responds to light1) Phototropism: Responds to light

Plants:Plants:Tropisms (Responses): Tropisms (Responses):

2) Thigmotropism: Responds to touch2) Thigmotropism: Responds to touch


3) Gravitropism: Responds to gravity3) Gravitropism: Responds to gravity

Click here for link to cool videos online.Click here for link to cool videos online.


4) Hydrotropism: Responds to water4) Hydrotropism: Responds to water

CactusCactusRidges:

Expand to store more water when it rains

Thorns:

Protect against being eaten

No Leaves:

Prevent water loss

Waxy Covering:

Prevent water loss

Flowers:

Can reproduce Sexually as well as asexually

Polar BearPolar Bear

Large Paws:

Walking on snow

Short/small Ears:

Save Heat

Long Claws:

Catching prey/digging

White/clear Fur:

Blend in with snow

Thick Blubber:

Keep warm

Adaptation PromptAdaptation PromptDraw an organism and describe the adaptations that Draw an organism and describe the adaptations that

make it “fit” (as in ‘fitness,’ ‘survival of the fittest’).make it “fit” (as in ‘fitness,’ ‘survival of the fittest’).

1.) Organism must be drawn, in color, & neat1.) Organism must be drawn, in color, & neat

2.) Must include background environment2.) Must include background environment

3.) Must have at least 3 adaptations w/ explanation of 3.) Must have at least 3 adaptations w/ explanation of advantage for survival/reproduction advantage for survival/reproduction

NotNot adaptations: adaptations: How long they live, where they How long they live, where they live, what they eatlive, what they eat

Adaptation examples:Adaptation examples:

* Large paws, thick beak, bright colored feathers, skinny * Large paws, thick beak, bright colored feathers, skinny legs, large ears, sharp teeth, fur thickness….legs, large ears, sharp teeth, fur thickness….

Hint: Must be clearly related to survival or reproduction!! Hint: Must be clearly related to survival or reproduction!!

Another example to demonstrate these Another example to demonstrate these selection patterns: selection patterns:

http://bcs.whfreeman.com/thelifewire/content/chp23/2302001.html

http://devour.com/video/the-http://devour.com/video/the-evolution-of-life-on-earth/ evolution-of-life-on-earth/

The The EndEnd

evolution. what is evolution? evolution, or change over time, is the process by which modern...

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charles darwin

dry islands

wetter islands

drier islands

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tortoises shell

groundgalapagos tortoises

giant tortoises